1. Field of the Invention
The present invention relates to electrodeposition such as is practiced in the automotive industry.
2. Description of the Art Practices
Electrodeposition is defined as the process of depositing a film forming material through the use of electrical potential. There are two forms of electrodeposition. The first and most widely known and used form is that of anodic deposition wherein the negatively charged film forming material is attracted to the anode where the negative charge is removed and the material is plated out. The second form of electrodeposition is known as cationic deposition wherein the film forming material contains a positively charged group which is attracted to the cathode. At the cathode the positive charge of the film forming material is neutralized by the electrons flowing through the electrode and the film is deposited thereon. In either the case of cationic or anodic electrodeposition a second cure, usually thermal, is employed to fix the film forming material onto the desired surface. In either instance, of course, the substrate to which the film is applied was the electrode involved in the reaction.
Considerable discussion of the subject of both cationic and anodic electrodeposition is found in THE CHEMISTRY OF BINDERS FOR ELECTRODEPOSITION found in PROGRESS IN ORGANIC COATINGS, 7(1979) Pages 1-77. Specific systems which discuss cationic electrodeposition are found in U.S. Pat. No. 3,922,253 issued Nov. 25, 1975 to Jerabek et al.
U.S. Pat. No. 3,637,618 issued Jan. 25, 1972 to May discloses compositions comprising a mixture of a curable unsaturated polyester which is formed from a normally liquid polyepoxide and an ethylenically unsaturated organic carboxylic acid and a second normally solid polymeric material possessing a plurality of epoxy groups. U.S. Pat. No. 3,876,518 issued Apr. 8, 1975 to Borden et al describes amine derivatives of acrylated epoxidized soybean oil which may be cured by radiation. Polyepoxide products which are formed from a blend of an epoxide resin and a polyacrylate or polymethacrylate and which are stated to have rapid low cure properties with polyamines are described in U.S. Pat. No. 4,051,195 issued Sept. 25, 1977 to McWhorter.
In U.S. Pat. No. 3,617,458 issued to Brockman Nov. 2, 1971 there are described cross-linkable coating compositions derived from an unsaturated compound containing a carboxylic acid, an epoxidized material and a compound which contains a pendant amine group. Bosso et al in U.S. Pat. No. 3,839,252 issued Oct. 1, 1974 describes compositions which are stated to be non-gelled water-dispersible epoxy resins containing oxyalkylene groups. U.S. Pat. No. 3,804,786 issued to Sekmakas issued Apr. 16, 1974 describes water-dispersible cationic polyurethane resins containing diglycidyl ether resins.
U.S. Pat. No. 3,935,087 issued to Jerabek et al on Jan. 27, 1976 describes coating compositions with good throwing power comprising epoxy resins with blocked isocyanates and amine salts. U.S. Pat. No. 3,963,663 issued to Sekmakas June 15, 1976 describes corrosion resistant thermosetting resins prepared by combining the water-dispersible foam of an acid and an amine resin and a phenolic resin McGinniss in U.S. Pat. No. 3,975,251 issued Aug. 17, 1976 describes heat curable coating compositions containing a polymer having pendant amine groups.
Marchetti et al in U.S. Pat. No. 3,975,250 issued Aug. 17, 1976 describes electrodeposition compounds containing mono-substituted urea and urethane linkages. The compounds are also stated to contain epoxy and acid solubilized amine groups. Cathodically depositable coating compositions are described by Bachmann et al in U.S. Pat. No. 3,729,435 issued Apr. 24, 1973. Jerabek in U.S. Pat. No. 4,031,050 issued June 21, 1977 describes cationic electrodepositable compositions containing a blocked isocyanate and the acid salt of an adduct of amine and a polyepoxide.
Throughout the specification and claims, percentages and ratios are by weight and temperatures are in degrees of Celsius unless otherwise indicated.